Messages in this thread | | | Date | Fri, 1 Aug 2014 19:00:35 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH 2/5] arm64, thunder: Add initial dts for Cavium Thunder SoC |
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On Fri, Aug 01, 2014 at 06:04:11PM +0100, Robert Richter wrote: > Mark,
Hi Robert,
> On 31.07.14 12:33:01, Mark Rutland wrote: > > On Thu, Jul 31, 2014 at 12:12:33PM +0100, Ganapatrao Kulkarni wrote: > > > We mark RAM used by ATF as secure-RAM, however we don't support > > > secure/non-secure address aliasing. > > > i.e, a DRAM address that can be referenced from both a secure PA and a > > > non-secure PA is not allowed. > > > > What exactly do you mean by "not allowed"? > > It actually means "not possible" since secure and non-secure memory is > kept in separate address ranges.
I understand that the two are separate physical address spaces, but Ganapatrao's reply was somewhat ambiguous and it wasn't clear to me that the memory was actually marked as secure.
> > If Linux maps that memory, what happens? > > > > What if Linux tried to read or write to it? > > > > If Linux should not map that memory, it should not be described in the > > memory map to begin with. > > Linux never will see secure-RAM. Firmware must be sure to report the > correct non-secure memory ranges to the OS (e.g. unsecure mem size = > total size - secure mem size).
Ok, that's what I had hoped for and that makes sense.
The issue was that the memory node contained an address range that was supposedly secure-only (which Linux could attempt to map), which was 'protected' with a /memreserve/ (which does not stop it from being mapped).
Given they are unnecessary (unless you want to bypass EFI for some reason) they can be dropped.
Thanks, Mark.
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